In a semiconductor product manufacturing process or a flat panel display (FPD) manufacturing process, a process in which a processing liquid is supplied to a semiconductor wafer or a glass substrate that is a substrate to be processed to perform a liquid processing is frequently used. For example, such a process involves a cleaning processing that removes, for example, particles and pollutants attached to the substrate.
As for a liquid processing apparatus that performs such a processing, a single wafer processing unit is known in which a substrate such as, for example, a semiconductor wafer is held on a spin chuck and a processing is performed by supplying a processing liquid (for example, a chemical liquid and a rinse liquid) to a front surface or front and back surfaces of the substrate in a state where the substrate is rotated.
The processing liquid supplied to the substrate is shaken off from the rotating substrate and scattered in the form of mist at a peripheral region of a substrate holding unit. Japanese Patent Laid-Open Publication No. H10-323633 discloses a substrate processing apparatus including a scattering prevention cup configured to guide the processing liquid shaken off from the substrate to a cleaning liquid collecting path to collect the scattered mist.
In such a substrate processing apparatus, it is necessary to perform a cleaning of the scattering prevention cup itself which collects the processing liquid shaken off from the substrate. As for a method for cleaning the cup, a method of using a disc-shaped cleaning substrate is known as disclosed in Japanese Patent Laid-Open Publication No. 2000-315671. In an apparatus disclosed in Japanese Patent Laid-Open Publication No. 2000-315671, the cleaning substrate is adsorbed and held on a spin chuck like the substrate and the cleaning substrate is driven to rotate. A cleaning liquid supplied to the central location of the top surface of the cleaning substrate from the upper side of the cleaning substrate is guided to the outside in a diameter direction along the top surface of the cleaning substrate by centrifugal force. Also, the cleaning substrate is provided with “set-up fins” at predetermined intervals along the peripheral direction in the vicinity of the outer peripheral edge of the cleaning substrate. The cleaning liquid is guided obliquely upward along the fins and scattered obliquely upward from the edge portions of the fins. Meanwhile, the cleaning liquid guided to a portion where the fins are not provided is scattered substantially in a horizontal direction from the edge portion of the top surface of the cleaning substrate.
Also, a cleaning jig disclosed in Japanese Patent Laid-Open Publication No. 2010-16315 may also be used as for a method of cleaning a cup configured to collect the processing liquid shaken off from the substrate. In the cleaning method of using a cleaning jig disclosed in Japanese Patent Laid-Open Publication No. 2010-16315, as illustrated in FIG. 8 of the publication, the cleaning liquid supplied to the central location of the bottom surface of the cleaning jig which is held by the spin chuck is guided to the outside in a diameter direction along the bottom surface of the cleaning jig by centrifugal force. The cleaning liquid turns around and enters along the outer peripheral surface of the cleaning jig and is scattered obliquely upward, thereby cleaning the cup.
However, the cleaning method of the cup using the cleaning substrate disclosed in Japanese Patent Laid-Open Publication No. 2000-315671 has a problem that since the cleaning liquid scattered obliquely upward from the edge portions of the fins and the cleaning liquid guided to a portion where the fins are not provided and scattered substantially in a horizontal direction from the edge portion of the top surface of the cleaning substrate interfere with each other, the cleaning liquid may not be supplied accurately to a required location and thus the cup may not be thoroughly cleaned. Also, the cup cleaning method using a cleaning jig as disclosed in Japanese Patent Laid-Open Publication No. 2010-16315 has a problem in that the cleaning liquid may not be supplied simultaneously to the several locations such as, for example, to both of inner and outer surfaces of the cup since there is only one path via which the cleaning liquid is supplied to the cup from the cleaning jig as illustrated in FIG. 8 of Japanese Patent Laid-Open Publication No. 2010-16315.